The present invention pertains to vibratory rollers for soil and backfill compaction and, more particularly, to an improved shaft assembly for a vibratory roller.
Vibratory rollers are well known in the utility and road construction industries for compacting backfill and other fill materials. Typically, such rollers include a large cylindrical roller drum attached to a piece of off-road equipment for movement over the surface to be compacted. A vibratory exciter shaft is mounted axially inside the drum, journaled to rotate independently of the drum and driven at high speed to impart vibratory motion to the drum to facilitate compaction. A vibratory roller may also be mounted with a scraper blade, such as shown in the apparatus of U.S. Pat. No. 5,062,228.
As shown in the above-identified patent and typical of the prior art, the exciter shaft comprises a solid steel shaft to opposite ends of which are welded aligned eccentric weights. It is also known to fasten the eccentric weights to the solid shaft with bolted connections. The opposite ends of the solid shaft are journaled in the end walls of the drum utilizing a bearing and seal arrangement. It has been found, however, that a solid steel eccentric shaft, having a typical diameter of about 3 inches (about 75 mm), is subject to excessive deflection at high speed rotation in the unsupported center of the shaft. This deflection is transmitted to the bearings and end seals, resulting in excessive misalignment, overheating, leakage and eventual failure of both the seals and bearings. Also, bolted connections are less reliable and more susceptible to failure then welds.
In accordance with the present invention, the prior art solid steel shaft is replaced by a hollow shaft of improved stiffness, yet lower weight, with an improved mounting for the eccentric weights and a lubrication system that is more effective and efficient.